The Effects of External Scattering on the Improvement of Random Lasers

The random laser (RL) emission characteristics can be improved by many different routes including either the material processing or optimizing the concentration of the relevant constituents. These routes can be very hard and even not practical in many cases, leaving us with the search of new schemes for the externally improvement of the random laser performance. In this paper, we suggest a simple approach for the externally enhancement of the random laser emission properties that can be applied in any designed transparent random lasing structures with single mode or multi-mode emission. This approach is based on using an adhesive tape in order to introduce an external scattering medium to the lasing structure and also return back the amplified leaking photons. For our investigated sample with nonresonant feedback, it is demonstrated that the emission intensity can be increased by a factor of 4.2 and the random laser threshold can be decreased by a factor of 1.8.